This section provides background information related to the present disclosure which is not necessarily prior art.
Plastic components are used in vehicles, such as automobiles, to provide reduced weight, cost, and increased corrosion resistance advantages, among other benefits. Many such plastic components are used for decorative purposes and thus have metal-coated surfaces. For example, chrome-plated surfaces comprise chromium and are commonly employed over plastic substrates. Accordingly, chrome-plated plastic materials are often used as decorative components, for example, in detailing, trim features such as grills, or as indicia of brands, logos, emblems, and the like. However, such decorative components are used in a wide variety of applications, such as consumer goods, appliances, reflector components, and the like, and are not limited to merely vehicles. Because chrome-plated plastic decorative components may be used in applications where they are exposed to moisture or other environmental conditions, including extreme weather conditions and exposure to UV radiation or corrosive agents, such chrome-plated plastic components may suffer from degradation or corrosion.
While chromium-containing surfaces have the ability to withstand corrosion under certain conditions, issues with surface corrosion on the chrome-plated surface may still occur. This is particularly true for automotive exterior components, because such chrome-plated surfaces may encounter significant moisture and other corrosive agents applied to road surfaces, such as deicing agents and dust suppression agents. The appearance of corrosion is unsightly to automobile owners and can create warranty issues. Thus, clear or colored paints are often applied over chrome-plated surfaces to provide additional protection. Colored or tinted organic polymer coatings containing a dye, pigment or other colorants formed over metal-plating can provide various distinct metallic finishes. However, organic paint coatings formed over chrome-plating have typically resulted in weak bonding and insufficient adhesion. Such painted chrome-plated plastic components have not been able to achieve sufficient robustness to be routinely used for exterior applications in vehicles. For example, the adhesion of current paint coatings applied over a chrome-plating tends to be insufficient to demonstrate necessary stone chip resistance or resistance to other routine physical forces, thus making it susceptible to not only chipping and other damage, but also ensuing corrosion.
Furthermore, over time many conventional paint and primer coatings are susceptible to degradation in the presence of water and other environmental conditions. Various conventional organic paint coatings have been observed to lose their initial adherence levels and bond strength to the underlying metal-coated substrate upon prolonged exposure to moisture/water. As such, paint over chrome has generally been considered a nonviable design option for surfaces of components that are exposed to extensive moisture, environmental and/or road conditions. It would be desirable to increase robustness of paint coatings formed over metal-coated plastic substrates, so that the organic paint coatings exhibit improved initial bond strength, have superior resistance to chipping and other minor physical damage, while also exhibiting sustained bond strength when exposed to water and various other environmental conditions.